Medical delivery catheters are well-known in the art of minimally invasive surgery for the introduction of fluids and devices to sites inside a patient's body. A well-established technique, known as “long wire guide,” is used for guiding a delivery catheter to a target site in a patient's body and it includes: (1) positioning a wire guide along a desired path to the target site; (2) retaining a proximal portion of the wire guide outside the body; (3) threading a delivery catheter, which has a wire guide lumen throughout its length, onto the proximal end of the wire guide; and (4) advancing the catheter along the wire guide to the treatment site.
One example of a desired path to a target site is the passage through a working lumen or channel of an endoscope to a biliary duct in a gastroenterological application. Another example of a desired path is through an endovascular lumen to an occluded coronary artery in a cardiology application. The delivery catheter may have a treatment device such as a stent or fluid-inflatable balloon disposed at its distal end for deployment at a target site (e.g., an occluded biliary duct or coronary artery). The catheter may also have a tool such as a cutting wire or cutting needle disposed at or near its distal end (e.g., a papillotome, sphincterotome, etc.), or the catheter may have an aperture for the delivery of a fluid through a second lumen (e.g., radio-opaque fluid for contrast fluoroscopy, adhesive or gelling agent for delivery to a target site, etc.).
Procedures that employ wire guides may require exchange of treatment appliances. For example, a balloon catheter may be replaced with a stent deployment catheter. In a typical application of such a procedure, a balloon catheter is directed to the site of a stenosis (e.g. in an artery, biliary duct, or other body lumen) as described above. Fluid is then used to inflate the balloon so as to dilate the stenosis. Some procedures are effectively concluded at this point. However, many procedures follow dilation of the stenotic stricture with the placement of a stent to maintain patency of the reopened lumen. This may require that the balloon catheter be withdrawn to allow for the introduction of a stent-deployment catheter (unless a stent placement catheter with an internal/placement balloon is used to accomplish both stenosis-dilation and stent-placement). It is preferable that the wire guide remain in place for guidance of the stent-deployment catheter without having to re-navigate the wire guide back into to the newly reopened lumen.
In order to prevent undesired displacement of the wire guide, any exchange of long wire guide catheters requires that the proximal portion of the wire guide extending out of the patient's body (or endoscope, depending on the entry point for the desired path to the target site) be longer than the catheter being “exchanged out,” so that control of the wire guide may be maintained as the catheter is being removed. Likewise, the wire guide must be grasped while the entire catheter being “exchanged in” is threaded onto it and directed along the desired path to the target site. In other words, for the operating physician and assistant to be able to hold the wire guide in place while removing one catheter for replacement with another, each of the catheters must be shorter than the portion of the wire guide that is exposed outside the patient's body (and, if used, outside the endoscope). Put another way, the wire guide must be about twice as long as a catheter that is being used over that wire guide. Additionally, in the case of gastrointestinal endoscopy, even more wire guide length is necessary. This is because the shaft of the endoscope through which the wire guide and catheters are placed must have a length outside the body for manipulation and control, and the catheter itself must have some additional length outside of the endoscope for the same reason. As those skilled in the art will appreciate, wire guides having the necessary “exchange length” are cumbersome and difficult to prevent from becoming contaminated.
An alternative technique for guiding a delivery catheter to a target site in a patient body utilizes catheters having a relatively short wire guide lumen in catheter systems commonly referred to as “rapid exchange,” “short wire guide,” or “monorail” systems. In such systems, the wire guide lumen extends only from a first lumen opening spaced a short distance from the distal end of the catheter to a second lumen opening at or near the distal end of the catheter. As a result, the only lumenal contact between the catheter's wire guide lumen and the wire guide itself is the relatively short distance between the first and second lumen openings. Several known advantages are conferred by this configuration. For example, the portion of the wire guide outside the patient's body may be significantly shorter than that needed for the “long wire configuration.” This is because only the wire guide lumen portion of the catheter is threaded onto the wire guide before directing the catheter through the desired path (e.g., a working lumen of an endoscope, an endoluminal passage, etc.) to the target site.
By way of illustration, the prior art catheters pictured in FIGS. 1A and 1B illustrate the distal ends of two different types of typical catheters. FIG. 1A shows the distal end of a prior art long-wire catheter shaft 100 with a wire guide 102 disposed in a lumen 104. The lumen 104 extends substantially to the proximal end (not shown) of the catheter shaft 100. In certain rapid exchange catheter configurations, the wire guide lumen is open to a side port aperture located on the side of the catheter between its proximal and distal ends. In one such configuration, the wire guide lumen only extends from the side port aperture to an opening at the distal end. An example of this type of rapid exchange catheter is illustrated in FIG. 1B.
FIG. 1B shows the distal end of a prior art short-wire catheter shaft 110 with a side port aperture 111 and a wire guide 112 disposed in a lumen 114. The length of the lumen 114, and consequently the exchange length of the catheter 110, is substantially shorter than that of the catheter 100 shown in FIG. 1A. In addition to a shorter exchange length, the catheter 110 (FIG. 1B) provides a reduced surface contact between the wire guide and catheter lumen that results in a reduced friction between the two. This can result in an eased threading and exchange process by reducing the time and space needed for catheter exchange. This economy of time and space is advantageous for minimally invasive surgeries since it reduces the likelihood of contamination and reduces the total time and stress of completing surgical procedures. On occasion, when advantageous, a catheter (such as, for example, the catheter 100 in FIG. 1A) may be left in place while the first wire guide is removed and replaced with a second wire guide; or, the wire guide lumen may be used for another purpose such as injecting a contrast media.
In another type of rapid exchange catheter configuration, the wire guide lumen extends through the length of the catheter from near its proximal end to its distal end. A side port aperture between the proximal and distal ends opens into the wire guide lumen. This side port aperture allows the catheter to be used in a short wire guide configuration, while the full-length wire guide lumen allows the catheter to be used in a long wire guide configuration. This wire guide lumen configuration is referred to as “convertible” or “dual use.” An example of this type of catheter is illustrated in FIG. 1C, which shows the distal end of a prior art “dual use” catheter shaft 120 with a wire guide 122 disposed through a side port aperture 121 and into a wire guide lumen 124. Specifically, a wire guide may run through substantially the entire length of the wire guide lumen, or the wire guide may run only through the portion of the lumen between the distal end and the side port aperture. In each of the described prior art embodiments, the side port aperture is located in a single, predetermined position relative to the ends of the catheter.
It would be advantageous to provide a catheter, such as an inflation balloon catheter, with a structure allowing multiple locations for the entry or exit of a wire guide for use in a rapid exchange configuration or long wire configuration.